Answers

it is difficult to figure out the problem only from this information, but there are a couple of hints:

The error simply states that there were no response from the HiveServer2 instance (specified by either the Master Address or the Hive Server Address fields, and the Hive Port) in a given time.

I would try the following:

Check the Hive log on the cluster. Does the SHOW TABLES command that the test sends appear in the log? (It can take seconds on first try.) That confirms that Hive may be accessible, but it may take longer time than the timeout.

If the log shows that the command was sent to Hive, then you can increase the timeout in Studio: go to Preferences -> Radoop, and increase the Connection timeout and Hive command timeout values to, let's say, 30. (These timeouts are used for detecting connection problems.)

If there is nothing in the log, then I would make sure that the specified address and port can be reached from the machine that runs Studio. If that works, I would check the health of Hive on the cluster from Beeline, for example.

The first thing is that JDBC URL Postfix field is only there for additional, custom postfix (the URL is constructed automatically). So it should be empty in your case. That could already solve the connection problem.

However, the java.lang.NoClassDefFoundError indicates that probably temporary files or folders (for example, usually in /tmp/ on Linux) of Studio may have been deleted, since the software has been started. Is that possible? If you keep getting this error, a Studio restart should help.

The address in the connection is localhost, does that mean that you are running Studio on the master node? (Beeline, of course, runs on the Hadoop node, but Studio may not.)

I would also make sure that 54310 is the port to use for the NameNode. If you navigate to localhost:50070, is that the port that the Overview page shows?